1. Field of the Invention
The present invention relates to an instrumentation system that is capable of accumulating measurement data and analyzing the data from various types of remotely-located analytical machines and instruments and, more particularly, to an efficient system for monitoring and collecting the data in an economical manner by a wireless system.
2. Description of Related Art
Various forms of instrumentation are used to monitor activities such as production processes. For example, the transient pH value of a liquid can be important to ensure proper production procedures. As shown in FIG. 7, a conventional general pH meter having a measuring electrode 71 is adapted to provide electrode signals through a highly insulating signal cable 73 to a meter 72. The meter 72 will receive the electrode signals and produce a display or recording of the measured results. As schematically shown in FIG. 7, an impedance conversion circuit 74 can receive an analog signal from the measuring electrode 71 and an A/D converter 75 can convert the analog signal into a digital signal. A computer system or CPU 76 can receive the digital signals for processing, and can be further powered by a power source such as a battery, shown as element 77.
Another example of a metering instrument is shown in FIG. 8 as meter 82. It can service a plurality of measuring electrodes 81 through the use of a switchover or changeover box 83, so that the respective outputs of the measuring electrodes 81 can be conveyed to the signal cables 84, and then through the switch mechanism 83 to the output cable 85. This instrument has the capacity of providing output signals from a number of separate measuring electrodes to a common meter 82.
In particular applications, a problem can occur in positioning the signal cables 73 and 84, as shown in FIGS. 7 and 8, when the sample liquid to be measured is preferably distant from the actual meters 72 or 83. In addition, it may be difficult to access the liquid sample. Also, as shown in FIG. 8, an additional disadvantage has occurred in that a significant number of cables 84 is increased, depending upon the number of desired measuring electrodes 81.
There have been suggestions to remotely monitor electrode signals, with the information being wirelessly transmitted to a remotely located meter, and the measured result being displayed on or recorded in the meter. In this regard, a single meter can service a plurality of measuring electrodes as disclosed in, for example, Japanese Utility Model Application Laid-Open No. Sho 59-84698. With this approach, a signal cable for connecting the measuring electrodes with the meter is unnecessary, and the measuring electrodes and the meter can be freely moved to a measuring site separately and independently.
However, when the electrode signals are converted from an analog to a digital format, and the measured data obtained as a result of this A/D conversion are wirelessly transmitted to the meter, a substantial expenditure of energy, considerably more than required for the A/D conversion, is consumed by the transmission of the electrical waves in a transmitting portion, as shown in the graph of FIG. 9. Thus, power consumption becomes a factor. In addition, in the case of a multichannel measurement, if transmitting intervals are made constant over all the channels when the measured data are being transmitted at the same frequency, the electrical waves are overlapped to disturb the normal receiving pattern, which can cause errors. Finally, a transmitting and receiving, or double direction communication, is not possible between the measuring electrodes and the meter in such an instrumentation system.
Thus, the prior art is still seeking to optimize a monitoring system for analytical instrumentation.